Direct broadcast systems use various orbital slots, which correspond to different services including video and audio programming. Additional new services are continuously being offered for direct satellite broadcast system users. Typically when new services are offered existing direct satellite broadcast system components need to be replaced or altered to accommodate for the new services. The services are broadcasted via radio waves within the direct broadcast system.
Typical direct broadcast systems include a direct broadcast receiver for receiving direct broadcast signals. The direct broadcast receiver includes a low noise block converter (LNB) or a series of individual separate LNBs. The LNB(s) may be directly connected to an integrated receiver and decoder (IRD) or may be connected to a multi-switch followed by one or more IRD(s). The LNB(s) receive, combine, and amplify the direct broadcast signals. A program channel is selected on the IRD(s), which in turn may directly receive a direct broadcast signal having a particular frequency corresponding to the program channel from a particular LNB or may use the multi-switch to switch to a different LNB.
Typically, 32 different frequencies are transmitted on any particular satellite. The satellite splits the frequencies between two polarizations, left hand circularly polarized (LHCP) signals and right hand circularly polarized (RHCP) signals to increase efficiency and allow the frequencies to be packed closer together given a certain amount of bandwidth allocated to each frequency. Use of the RHCP signals and LHCP signals allows for an increased number of frequencies to exist on the same bandwidth and increases capacity of the satellite. Half of the frequencies are assigned to the RHCP signals and the other half of frequencies are assigned to the LHCP signals.
Each LNB can only receive one of the polarizations at any particular time. Thus, a LNB typically receives 16 frequencies at any point in time. Received polarization is determined by a direct current (DC) voltage control mechanism that is applied to an output of the LNB(s). The DC voltage is either +13V or +18V dependent on the polarization desired. Each LNB can then select a desired polarization and convert the satellite signal at approximately 15 GHz and translate it in frequency down to 950-1450 MHz, or a 500 MHz wide signal band. The 500 MHz wide signal band is the signal that is normally fed into the IRD(s). Each IRD then selects one of the 16 frequencies from the input spectrum and one or more channels contained within the chosen frequency.
A site may have multiple IRD(s), typically internal to the customer site, each of which requiring a separate wire to connect to the multi-switch or LNBs. The multi-switch allows multiple IRD(s) to access the entire available spectrum, up to approximately 32 frequencies on each satellite, requiring each tuner to be coupled to the multi-switch with an associated wire. Also, each IRD may have multiple tuners, especially in more advanced IRD(s) that offer advanced consumer features, such as watch and record, picture-in-picture, and independently acquired data feed features. Thus, each tuner requires a designated wire since currently used selection mechanisms are not designed to operate in a shared medium environment. For example, a three-tuner IRD requires three wires. Separate wires are used for two main reasons. First the control mechanism is DC coupled, which can cause interference between tuners that are using a single wire. Second the transmitted signals received by each tuner are at the same frequencies and having the same bandwidths, also causing conflict between signals.
The multiple wires increase the number of required ports on multiple system components and potentially require increased hole size in an exterior wall of a building to accommodate for additional wires between the LNB(s) and the IRD tuners. The multiple wires not only increase installation complexity but also decrease system esthetics.
Also, in order to accommodate system upgrades, such as additional satellite access, advanced modulation schemes, newly introduced frequency spectrums, or other system upgrades, existing IRD(s) are often replaced and system wiring is expanded.
Additionally, existing direct broadcast systems are bandwidth inefficient in that communication signals are distributed from satellites to sites at a larger bandwidth than required or used by a particular site. The larger bandwidth is received by the LNBs and distributed to the IRD(s), which only use a portion of the bandwidth associated with desired customer services.
It would therefore be desirable to minimize the number of wires between LNBs and IRD(s) within a direct broadcast system, thereby potentially minimizing system installation complexity, minimizing system costs, and improving system esthetics. It would also be desirable for the direct broadcast system to support both existing daisy chain wiring and site-run wiring architectures, minimize system adjustments when different satellites or broadcast bands are utilized, and minimize system upgrade costs.